Relaxing curls with products

I'm a guy with shoulder-length thick, curly hair which isn't really frizzy but it dries forming these annoying tight little curls. So I just wear it in a ponytail. But ideally I would like to relax my curls - not to have my hair completely straight but to have much looser curls/waves. Does anybody know how I can achieve this by using products? Incidentally, I think my hair is in good condition as I don't brow dry and I've never dyed it, but I have a feeling it may naturally be what you'd call dry.